Method and system for automatic charging of electric vehicles

ABSTRACT

An electric charger resource sharing method and system comprise a charger that supplies electrical energy to a plurality of electric vehicles. The charger includes a robotic arm that articulates to be proximal to each of the electric vehicles for supplying the electrical energy to the electric vehicles and a docking interface at a distal end of the robotic arm that couples with a receptacle on each of the electric vehicles for transferring the electrical energy from the charger to the electric vehicles. A resource management device receives a bid from each electric vehicle, and allocates a portion of the electrical energy for a predetermined period of time to an electric vehicle of the plurality of electric vehicles in response to the bid of the electric vehicle.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a utility application claiming priority toco-pending U.S. Provisional Application Ser. No. 61/863,164 filed onAug. 7, 2013 entitled “METHOD AND SYSTEM FOR CHARGING ELECTRIC VEHICLES”the entirety of which is incorporated by reference herein. Thisapplication is related to U.S. Pat. No. 8,473,131 entitled “METHOD ANDSYSTEM FOR CHARGING ELECTRIC VEHICLES,” the entirety of which isincorporated by reference herein.

FIELD OF THE INVENTION

The invention relates generally to electric powered vehicles. Morespecifically, the invention relates to systems and methods for chargingelectric vehicles according to a dynamic allocation.

BACKGROUND

Electrically powered vehicles (EV) and battery electric vehicles (BEV)have numerous advantages over fossil fuel cars including reducedemission of pollutants and national dependency on foreign energysources. Despite these advantages, EVs suffer from short driving rangeand long charging intervals due largely to battery technologylimitations. Accordingly, both widespread adoption of EVs and a charginginfrastructure has been limited. Hybrid electric vehicles (HEV) orplug-in hybrid electric vehicles (PHEV) attempt to mitigate the rangeand charging interval issues by providing an alternate power source, forexample fossil fuel or hydrogen.

Typical electric charging stations require the vehicle user to manualconnect the car to the station. With the required frequency of chargingsuch manual intervention complicates vehicle ownership and thus vehicleadoption.

Another approach uses near field magnetic resonance induction. Thisapproach suffers from electromagnetic interface and lower couplingefficiency between the power source and the vehicle.

To fully realize the potential of EVs and encourage their adoption,charging should occur with limited or no user intervention as anunconscious task. This requires an intelligent system to transfer powerbetween a variety of power sources and the vehicle. In addition, thereneeds to be a way to appropriately bill for this service regardless ofwho is driving the vehicle as would occur with a rental fleet.

BRIEF SUMMARY

In one aspect, the invention features a method for charging an electricvehicle. The presence of an electric vehicle proximate to a charger isdetermined. The user account data associated with the electric vehicleis validated. A docking interface on the charger is aligned to areceptacle on the electric vehicle. The docking interface is coupled tothe receptacle when a proximity is less than a predetermined distance.Power is supplied from the charger to the electric vehicle.

In another aspect, the invention features an electric charger resourcesharing system, comprises a charger that supplies electrical energy to aplurality of electric vehicles. The charger includes a robotic arm thatarticulates to be proximal to each of the electric vehicles forsupplying the electrical energy to the electric vehicles and a dockinginterface at a distal end of the robotic arm that couples with areceptacle on each of the electric vehicles for transferring theelectrical energy from the charger to the electric vehicles. A resourcemanagement device receives a bid from each electric vehicle, andallocates a portion of the electrical energy for a predetermined periodof time to an electric vehicle of the plurality of electric vehicles inresponse to the bid of the electric vehicle.

In another aspect, the invention features a method for selecting anelectric vehicle for receiving an allocation of a charging resource. Themethod comprises selecting each of a plurality of electric vehicles as acandidate for receiving an allocation of a charging resource for apredetermined period of time; generating a bid value for each of theplurality of electric vehicles; and selecting one of the electricvehicles for receiving the allocation of the charging resource for thepredetermined period of time in response to the bid value correspondingto the one of the electric vehicles.

In another aspect, the invention features a computer program product forselecting an electric vehicle for receiving an allocation of a chargingresource, comprising: a computer readable storage medium having computerreadable program code embodied therewith. The computer readable programcode comprises computer readable program code configured to select eachof a plurality of electric vehicles as a candidate for receiving anallocation of a charging resource for a predetermined period of time;computer readable program code configured to generate a bid value foreach of the plurality of electric vehicles; and computer readableprogram code configured to select one of the electric vehicles forreceiving the allocation of the charging resource for the predeterminedperiod of time in response to the bid value corresponding to the one ofthe electric vehicles.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The above and further advantages of this invention may be betterunderstood by referring to the following description in conjunction withthe accompanying drawings, in which like numerals indicate likestructural elements and features in various figures. The drawings arenot necessarily to scale, emphasis instead being placed uponillustrating the principles of the invention.

FIG. 1 is a perspective view of an embodiment of a system for chargingelectric vehicles according to the invention.

FIG. 2 is a perspective view of an electric vehicle and a chargerillustrated in FIG. 1.

FIG. 3A is a perspective view of an embodiment of a docking interface.

FIG. 3B is a perspective view of an embodiment of a receptacle usablewith the docking interface in FIG. 3A.

FIG. 3C is a cross-sectional view of FIG. 3A taken along A-A′, furtherillustrating a spring-loaded imager and an electromagnet.

FIG. 4A is a perspective view of an embodiment of a docking interface.

FIG. 4B is a perspective view of an embodiment of a receptacle usablewith the docking interface in FIG. 4A.

FIG. 4C is a cross-sectional view of FIG. 4A taken along B-B′, furtherillustrating the spring-loaded imager.

FIG. 5 is a perspective view of the embodiment of the docking interfacein FIG. 4A modified to move the imager.

FIG. 6 is a perspective view of the embodiment of the docking interfacein FIG. 4A in relation to three axis defining the six degrees offreedom.

FIGS. 7A, 7B and 7C illustrate coaxial alignment using features on areceptacle.

FIGS. 8A and 8B illustrate the proximity of a receptacle in the field ofview.

FIGS. 9A and 9B illustrate the roll alignment using features on areceptacle.

FIGS. 10A and 10B illustrate the pitch alignment of a receptacle in thefield of view.

FIGS. 10C and 10D illustrate the yaw alignment of a receptacle in thefield of view.

FIG. 10E illustrates a receptacle with coaxial misalignment, rollmisalignment, pitch misalignment and yaw misalignment.

FIG. 11 is a schematic view of an embodiment of a mesh network accordingto the invention.

FIG. 12 is a schematic view of an embodiment of a metering architectureaccording to the invention.

FIG. 13A is a schematic view of the mesh network in FIG. 11 showing acommunication path.

FIG. 13B is a schematic view of the mesh network in FIG. 13A showing arepaired communication path.

FIG. 14A is an illustrative front view of two electric vehicles proximalto a charger at a parking location, in accordance with an embodiment.

FIG. 14B is a top view of the two electric vehicles proximal to thecharger at a parking location shown in FIG. 14A.

FIG. 15A is a view of the charger of FIGS. 14A and 14B in a closedstate, in accordance with some embodiments.

FIG. 15B is a view of the charger of FIGS. 14A, 14B, and 15A in an openstate, in accordance with some embodiments.

FIG. 16A is an illustrative view of four electric vehicles proximal to acharger at a parking location;

FIG. 16B is a top view of one of the four electric vehicles proximal tothe charger of FIG. 16A.

FIG. 17 is a flowchart of a method for dynamic allocation of a chargingresource, in accordance with some embodiments.

FIG. 18 is a flowchart of a method for determining a bidder forreceiving an allocation of a charging resource, in accordance with someembodiments.

FIG. 19 is a diagram of a kinematic model of a charger, in accordancewith an embodiment.

FIG. 20 is a diagram of the kinematic model of FIG. 19 and correspondingelements of a charger, in accordance with an embodiment.

FIG. 21 is a table illustrating a comparison of utilization of chargerresources, in accordance with some embodiments.

DETAILED DESCRIPTION

Embodiments of charging methods and systems described herein provide forintelligent power management between a power grid and an electricvehicle (EV) including combinations of vehicle charging and use of thevehicle to return power to the grid. The embodiments described hereinrefer to EV. An EV can include a battery electric vehicle (BEV), hybridelectric vehicle (HEV), plug-in hybrid electric vehicle (PHEV) and anytransportable device that generates or consumes electricity and benefitsfrom autonomous charging. For example, an EV can be a golf-cart, afork-lift or an electric shopping-cart. Autonomous means that the act ofcharging the EV or sharing the EV power with the power grid occurs withlittle or no user action. In so doing, the limitations of frequent andlong charging intervals associated with EVs, relative to fossil fuelvehicles disappears thereby facilitating the widespread adoption of EVs.

In one embodiment a user parks an EV at a work site and leaves the EV.In another embodiment the EV is parked at home and the user goes tosleep. A robotic charger detects the presence of the vehicle. Accountdata associated with the EV either contained in a key, on a receptacleon the EV or both are transmitted wirelessly to a resource thatvalidates whether the grid should charge the car, whether the car shouldcharge the grid and manages billing information. The charger connects tothe EV using machine vision and charging proceeds until the user returnsto the car, a full charge occurs or some other event terminates thecharging process. At this time the charger undocks and stows awayawaiting the next EV.

FIG. 1 illustrates an embodiment of a charging system 10 for four EVs 12a, 12 b, 12 c and 12 d (generally 12) each having a correspondingreceptacle 18 a, 18 b, 18 c and 18 d (generally 18) respectively. In oneembodiment each EV 12 has more than one receptacle to facilitatecoupling to the charger. Each EV 12 is shown at various stages ofdocking with chargers 14 a, 14 b, 14 c and 14 d (generally 14). Eachcharger 14 has a corresponding docking interface 16 a, 16 b, 16 c and 16d (generally 16) used to couple with the corresponding receptacle 18 onthe EV 12.

Each EV 12 and each charger 14 communicates wirelessly with acoordinator 30. The coordinator 30 communicates through an Internet 34by way of an Internet gateway 32. The Internet connects to a pluralityof resources including computers 36 a and 36 b (generally 36). TheInternet 34 may also be a cloud-computing environment where a largenumber of resources, for example computers, are in communication withthe Internet gateway 32. The Internet gateway 32 is preferably aruggedized tablet personal computer (PC) but may also be any computingdevice capable of passing low data rate files between the coordinator 30and the Internet 34.

The wireless communication preferably uses the Institute of Electricaland Electronic Engineers (IEEE) 802.15.4 standard (Zigbee™). Zigbee™ isoptimal for control and sensor networks that have low data rate, lowpower consumption and small packet sizes. Other wireless protocols maybe used in place of, or in combination with, Zigbee™ including but notlimited to MiWi™, ANT™, IEEE 802.15.1 (Bluetooth®), IEEE 802.11 (WiFi™),IEEE 802.16 (WiMax™), and Long Term Evolution (LTE™).

Each charger 14 also communicates with a power grid 20, which connectsto numerous electric power sources, for example a wind turbine 22, acoal burning power plant 24 or an array of solar cells 26. Preferablythe chargers 14 support either Level-1 (e.g. single phase 120V), Level-2(e.g. single phase 230/240V) or any Level-3 (e.g. three phase) powerstandard, although the chargers 14 are envisioned to be usable with anypower line standard available including different frequencies such as 50Hz and 60 Hz.

The charging system 10 of FIG. 1 illustrates the various stages ofdocking or coupling a receptacle 18 on an EV 12 with a docking interface16 on a charger 14. EV 12 a has just arrived at a parking spot. Charger14 a senses the proximity of EV 12 a when a wireless signal transmittedfrom EV 12 a is strong enough to be detected by charger 14 a anddetermined to be of sufficient magnitude. The charger 14 a also ensuresthat the EV 12 a is stationary before attempting to dock. Charger 14 amay also use auto-ranging techniques including sonar or measuring theacoustic delay of a signal transmitted by the charger 14 a, reflected bythe EV 12 a and returned to the charger 14 a. In other embodiments theauto-ranging may measure the delay of a light beam or sense the magneticfield distortion when a magnetic field emitted by the charger 14 a isproximate to metal contained in the EV 12 a.

In addition to sensing proximity of the EV 12 a to the charger 14 a, theroll angle of the EV 12 a is transmitted to the charger 14 a tofacilitate subsequent docking of the docking interface 16 a to thereceptacle 18 a. The roll angle of the EV 12 a is measure of how muchthe EV 12 a leans left or right, for example when the EV 12 a is parkedon a sloped surface. The EV 12 a also transmits other charging behaviordata, for example the date when the EV 12 a was charged, the time andduration when the EV12 a was charged and the location where the EV12 awas charged. The EV12 a also transmits information for billing purposessuch as billing address and account data in a secure encrypted format.In one embodiment, the encryption format is a 128-bit encryption basedon the National Institute of Standards and Technology (NIST) CertifiedAdvanced Encryption Standard (AES). Information transmitted by the EV 12a is received by the coordinator 30 and passed to the Internet gateway32 for account validation and billing purposes or to determine if the EV12 a should supply power to the power grid 20 based on the chargingbehavior of the EV 12 a. For example, if the EV12 a has excess charge oris expected to remain parked for a long time based on previous chargingsessions the EV 12 a could supply power to the power grid 20 when thereis high demand for power from other EVs connected to the power grid 20.The account corresponding to the EV 12 a is credited at a favorablebilling rate compared to the billing rate used when the EV 12 apreviously received power from the power grid 20. In another embodimentthe information transmitted by the EV 12 a to the coordinator 30 is usedto assess a parking fee for the EV 12 a. In yet another embodiment theEV 12 a can alert the driver of the EV of a potential theft of the EV bysending a signal to the Internet 34 when the EV is moved.

Supplying power from the EV 12 to the power grid 20 is compatible withvehicle to grid (V2G). V2G reduces the demand on power sources 22, 24and 26 because a large pool of EVs 12 can supplement the powergeneration of the power sources 22, 24 and 26. The autonomous nature ofthe charging system 10 improves V2G because an accurate determination ofwhen, where and how to transfer power from an EV 12 to the power grid 20requires a charging behavior usage database that contains a significantnumber of charging sessions. This in turn necessitates a system asdescribed with charging system 10 that is easy to use and collects thenecessary data for effective V2G without user intervention or manualerror.

EV 12 b is at the next stage of docking compared to EV 12 a. The dockinginterface 16 b on charger 14 b is aligned to the receptacle 18 b on EV12 b by positioning the docking interface with a robotic arm on thecharger 14 b. The robotic arm is capable of articulated movement withsix degrees of freedom (sixDOF) and a telescoping arm. Robotic arms withadditional degrees of freedom are also envisioned. While preferably asixDOF robotic arm is used, certain installations may advantageously usea robotic arm with more joints to clear obstacles between the charger 14b and the EV 12 b.

EV 12 c is at the next stage of docking compared to EV 12 b. After theinitial alignment stage illustrated with EV 12 b, and when the dockinginterface 16 c is within close proximity to the receptacle 18 c, thedocking interface 16 c is coupled to receptacle 18 c. During thecoupling, the alignment of docking interface 18 c to the receptacle 18 cis maintained until coupling is complete. The proximity of dockinginterface 16 c to the receptacle 18 c is sufficiently close when lessthan a predetermined distance that is defined by a value stored in thecharger 14 c.

Determining the proximity of the docking interface 16 c to thereceptacle 18 c is based on methods similar to the initial determinationthat EV 12 a was sufficiently close to charger 14 a. Specifically, thecharger 14 c may use auto-ranging techniques including sonar ormeasuring the acoustic delay of a signal transmitted by the charger 14c, reflected by the EV 12 c and returned to the charger 14 c. In otherembodiments the auto-ranging may measure the delay of a light beam orsense the magnetic field distortion when a magnetic field emitted bycharger 14 c is proximate to metal contained in EV 12 c.

In one embodiment, coupling of the receptacle 18 c with the dockinginterface 16 c includes achieving a physical connection betweenelectrodes on the receptacle 18 c and electrodes on the dockinginterface 16 c. In another embodiment, the receptacle 18 c couples tothe docking interface 16 c with a magnetic field with power transferredthrough near-field inductive coupling. In yet another embodiment, thereceptacle 18 c couples to the docking interface 16 c with anoptocoupler. Once the receptacle 18 c is coupled to the dockinginterface 16 c, the charger 14 c performs supplies power from the powergrid 20 to the EV 12 c, supplies power from the EV 12 c to the powergrid 20, or both. In one embodiment, the charger 14 c contains a currentlimit device to lower the charging rate with a corresponding reductionin billing charges.

EV 12 d is at the next stage of docking compared to EV 12 c. The EV 12 dis charged by charger 14 d. The EV 12 d signals the end of a chargingsession expressly or as a fail-safe when the EV 12 d begins to move. Thecharger 14 d then stores the robotic arm as depicted with charger 14 a.

In addition to charging the EV 12 or returning power to the power grid20 with V2G, the charging system 10 also enables a user to control adevice of the EV 12 by sending a control signal through the Internet 34to the coordinator 30 to be communicated to the EV 12. In one embodimentthe control signal received by the EV 12 controls the EV 12 airconditioning, heating and lighting systems by further communicating withthe EV 12 controller area network (CAN) or local interconnect network(LIN) bus. A CAN or LIN bus provides communication between a variety ofdevices in an EV such as heating systems, lighting and radios. Thecontrol signal received by the EV 12 is beneficial to start a car towarm the cabin before a driver arrives or to activate lights to locate acar in a crowded lot for example.

FIG. 2 further illustrates the docking interface 16 b on charger 14 baligning to the receptacle 18 b on EV 12 b as shown in FIG. 1. In oneembodiment the receptacle 18 b is on the front of the EV 12 b. In otherembodiments, the receptacle 18 b is on the rear or on the side of the EV12 b. In yet another embodiment, multiple receptacles are available forthe charger 14 b to choose from based on proximity.

FIG. 3A shows an embodiment of a docking interface 52 with a pluralityof electrical connectors 56, an electromagnetic surface 60 and an imager64. The surface 60 is magnetized by an electromagnet that is powered bythe charger 14 when docking the charger 14 to the EV 12. After chargingis complete, the electromagnet is deactivated thereby facilitating theundocking of the charger 14 to the EV 12. The electrical connectors 56include a combination of power, ground and signals. In one embodimentthe imager 64 is responsive to infrared light and contains a field ofview sufficient to see the receptacle 16 during docking as illustratedin FIG. 1.

FIG. 3B shows an embodiment of a receptacle 54 with a plurality ofelectrical receptors 58, a magnetized surface 62, a west feature 66, anorth feature 68, an east feature 70 and a centroid feature 72 mountedon a pedestal 74. In one embodiment the length of the pedestal 74 isapproximately the same as the distance between the west feature 66 andthe east feature 70, which is 74 mm in one instance. The dockinginterface 52 shown in FIG. 3A is a female connector and the receptacle54 shown in FIG. 3B is a male connector. It is contemplated that thedocking interface 52 may be a male connector and the receptacle 54 afemale connector, or the docking interface 52 may be a female connectorand the receptacle 54 a male connector. The electrical connectors 56 andthe electrical receptors 58 are designed to couple with a friction fithowever they may also be capacitively coupled or inductively coupled tofurther isolate the EV 12 from high voltages for safety reasons. In onealternative embodiment the surface 62 on the receptacle 54 is anunmagnetized metallic surface. In another embodiment the surface 62 isan electromagnet powered by the EV 12 when docking the charger 14 to theEV 12 and the surface 60 on the docking interface 52 is either metallic,a permanent magnet or an electromagnet.

Features 66, 68, 70 and 72 may be reflective emblems illuminated by alight source in the docking interface 52, or may be light emittingdiodes (LEDs) or a light pipe formed by a fiber optic thread illuminatedby a light source. In one embodiment the LEDs are preferably infraredLEDs with a 7.5 Hz square-wave amplitude modulation. The LED frequencyand modulation scheme is preferably chosen to be responsive to emissionsfrom the receptacle features and not responsive to ambient light or heatsources that may interfere with the receptacle emissions. In anotherembodiment additional features are present to provide redundancy in casea feature is obscured or to achieve increased accuracy.

In one embodiment, the imager 64 of the docking interface 52 has a wipermechanism to keep the imager 64 free of dirt and snow. Alternatively,the imager 64 of the docking interface 52 has an iris shutter to keepthe imager 64 free of dirt and snow. In another embodiment, the imager64 of the docking interface 52 has forced hot air blown across itthrough one of the electrical connectors 56. A heater and blower on thecharger 14 provides a flow of heated air through a tube from the charger14 to one of the connectors 56. In another embodiment, the imager 64 isheated with a thermostatic heater. Specifically, the spring 76 in FIG.3C is heated and heat is conductively transferred to the imager 64.

FIG. 3C shows the cross-section of FIG. 3A taken along A-A′ andillustrates the electrical connector 56 with a friction fit adapted toreceive an electrical receptor 58 on the receptacle 54. The imager 64 isspring-loaded by a spring 76 and communicates with the charger 14 ofFIG. 1 with signals 78. The spring 76 is a low compression force springallowing the pedestal 74 of receptacle 54 to compress the spring 76during the docking process. Docking interface 52 has an electromagneticsurface 60. The polarization of the surface 60 can be removed orreversed after charging of the EV 12 or transferring power to the powergrid 20 is complete.

FIG. 4A shows a modification of the embodiment of the docking interface82 shown in FIG. 3A, where the imager 64 is contained in a threaded hole88. FIG. 4B shows a modification of the embodiment of the receptacleshown in FIG. 4B where the pedestal contains threads 86 adapted tocouple with the threaded hole 88 shown in FIG. 3A.

FIG. 4C shows the cross-section of FIG. 4A taken along B-B′. FIG. 4C issimilar to FIG. 3C with the exception that the electromagnetic surface60 in FIG. 3C is absent. The docking interface shown in cross-section inFIG. 4C uses a threaded screw or auger formed by the threaded pedestal86 on receptacle 84 to couple to the threaded hole 88 of dockinginterface 82. In one embodiment, the threaded pedestal 86 is powered bythe receptacle 84 to rotate during the docking session and to stoprotating when the docking interface 82 and the receptacle 84 arecoupled, determined by conduction between one of the electricalconnectors 56 and one of the electrical receptors 58.

FIG. 5 is a modification to the docking interface 82 shown in FIG. 4Awhere the imager 64 is offset from the centroid feature 72 shown in FIG.4B. Advantageously, this embodiment does not require the spring 76 shownin FIG. 3C but requires accurate ranging information to establish thedistance between the docking interface 82 and receptacle 84 duringdocking, and the distance between the threaded hold 88 and the imager 64to compensate for the imager 64 offset during alignment of the dockinginterface 82 and the receptacle 84.

FIG. 6 shows an embodiment of the docking interface 82 of FIG. 4A inrelation to the three axis defining the six degrees of freedom (sixDOF).To properly align the docking interface 82 with the receptacle 84 shownin FIG. 4A and FIG. 4B respectively the docking interface 82 is alignedto the receptacle 84 in six ways. First, the docking interface 82achieves coaxial alignment by correcting for horizontal misalignment onaxis 102 and vertical misalignment on axis 104. Second, the dockinginterface 82 reduces proximity to the receptacle 84 by moving along axis106. Third, the docking interface 82 achieves roll 107 alignment.Fourth, the docking interface 82 achieves pitch 108 alignment. Fifth,the docking interface 82 achieves yaw 109 alignment. Each of the sixDOFmay be interdependent and require concurrent alignment or each of thesixDOF may be adjusted iteratively.

FIGS. 7A, 7B and 7C illustrate a method of coaxially aligning thedocking interface 82 of FIG. 4A to the receptacle 84 of FIG. 4B. In FIG.7A, the imager 64 shown in FIG. 4A sees four features: the centroidfeature 72, the west feature 66, the north feature 68 and the eastfeature 70. In FIG. 7A, the docking interface 82 is north-west of thereceptacle 84 and should be moved to the right and downward to maintainan equal distance between the centroid feature 72 and each of the westfeature 66, the north feature 68 and the east feature 70. In FIG. 7B,the docking interface 82 is east of the receptacle 84 and should bemoved to the right to maintain an equal distance between the centroidfeature 72 and each of the west feature 66, the north feature 68 and theeast feature 70. In FIG. 7C, the docking interface 82 has achievedcoaxial alignment with the receptacle 84.

FIGS. 8A and 8B illustrate a method of achieving proximity of thedocking interface 82 of FIG. 4A to the receptacle 84 of FIG. 4B towithin a predetermined distance. In FIG. 8A, the receptacle 84 is farfrom the docking interface 82 relative to the receptacle 84 shown inFIG. 8B because the distance between the west feature 66 and the eastfeature 70 is small in comparison to the field of view 126 of the imager64 shown in FIG. 4A. By increasing the distance between the west feature66 and the east feature 70, the docking interface 82 is positionedcloser to the receptacle 84 as shown in FIG. 8B.

While preferably the west feature 66 and the east feature 70 are used toachieve proximity, maximizing the distance between any two features onthe receptacle 84 similarly results in positioning the docking interface82 closer to the receptacle 84. For example, maximizing the distancebetween the centroid feature 72 and the west feature 66 ultimatelyresults in moving the docking interface 82 closer to the receptacle 84even though a concurrently performed coaxial alignment shown in FIGS. 7Band 7C may temporarily interfere with the proximity adjustment, untilcoaxial alignment is achieved.

FIGS. 9A and 9B illustrate a method of achieving roll alignment of thedocking interface 82 of FIG. 4A to the receptacle 84 of FIG. 4B.Specifically, FIG. 9A shows the features on a receptacle 84 rolled aboutthe axis 106 shown in FIG. 6, while FIG. 9B shows the same features on areceptacle 84 after roll alignment is achieved. Preferably an alignmentline intersecting the west feature 66 and the east feature 70 iscompared with a reference line stored in the charger 14 a of FIG. 1. Thereference line stored in the charger 14 a is modified by the roll angleof the EV 12 a to compensate for sloped parking surfaces.

While preferably the west feature 66 and the east feature 70 are used toform the alignment line used for roll alignment, it is contemplated thatthe alignment line can intersect any two features. Similar to theinteraction of concurrently performing coaxial alignment and achievingproximity, the use of the centroid feature 72 and the west feature 66,(or similarly the east feature 70), may cause an interaction betweenroll alignment and coaxial alignment but ultimately both roll alignmentand coaxial alignment are achieved.

FIGS. 10A and 10B illustrate a method of achieving pitch alignment ofthe docking interface 82 of FIG. 4A to the receptacle 84 of FIG. 4B.FIG. 10A shows the features of the receptacle 84 shifted to the top ofthe field of view 126 of the imager 64. Pitch alignment is achieved bymoving the centroid feature 72 downward to the center of the field ofview 126. FIG. 10B shows the features of the receptacle 84 shifted tothe bottom of the field of view 126 of the imager 64. Pitch alignment isachieved by moving the centroid feature 72 upward to the center of thefield of view 126.

FIGS. 10C and 10D illustrate a method of achieving yaw alignment of thedocking interface 82 of FIG. 4A to the receptacle 84 of FIG. 4B. FIG.10C shows the features of the receptacle 84 shifted to the left of thefield of view 126 of the imager 64. Yaw alignment is achieved by movingthe centroid feature 72 rightward to the center of the field of view126. FIG. 10B shows the features of the receptacle 84 shifted to theright of the field of view 126 of the imager 64. Yaw alignment isachieved by moving the centroid feature 72 leftward to the center of thefield of view 126.

FIG. 10E shows the features of a receptacle 84 with coaxialmisalignment, proximity less than a predetermined distance, rollmisalignment, pitch misalignment and yaw misalignment. Each of thesixDOF alignments shown in FIG. 6 can be adjusted concurrently with oneor more of the other sixDOF alignments, or each of the sixDOF alignmentscan be adjusted independently and iteratively. In one embodiment, aninitial pitch alignment and a yaw alignment occur first to move thefeatures on the receptacle 84 to the center of the field of view 126.This advantageously improves the accuracy of subsequent alignment stepsby using the center of the field of view 126 of the imager 64, whereless lens distortion and parallax occurs.

The field of view 126 is designed to cover sufficient area to initiallysee the features of the receptacle 84. In other embodiments, the imager64 includes a zoom feature to create a wider field of view 126 tofacilitate initial image capture. In another embodiment, the charger 14of FIG. 1 performs a raster scan movement to facilitate initial imagecapture. The raster scan movement begins at the top left of the field oftravel of the charger 14, moves from left to right, moves downward byless than the height of the field of view 126, scans right to left,moves downward by less than the height of the field of view 126 andrepeats the above steps.

FIG. 11 illustrates a mesh network 170 used for simple, scalable andfault tolerant communication between components of a charging systemdescribed herein. FIG. 11 shows three EVs 12, each with a smart key 174and a charger 14. Each charger 14 and each EV 12 is capable of being awireless router, which means it can retransmit information at therequest of other components. Each smart key 174 is a wireless end-point,which means it can respond to a request, but does not retransmitinformation on behalf of other components, thereby extending the batterylife of the smart key 174. A smart key 174 can be a single integratedcomponent or can be a separate module carried on a key chain.

The mesh network 170 includes three chargers 14 acting as chargerrouters 180, 180 b and 180 c (generally 180), three EVs 12 acting as EVrouters 176 a, 176 b and 176 c (generally 176) and three smart keys 174acting as smart key endpoints 172 a, 172 b and 172 c (generally 172).Each charger router 180 can retransmit data from any other chargerrouter 180, any other EV router 176 and the coordinator 30. Each EVrouter 176 can retransmit data from any other EV router 176, any chargerrouter 180, any smart key endpoint 172 and the coordinator 30. Eachsmart key endpoint 172 cannot retransmit data but can respond to arequest from any EV router 176 or the coordinator 30. For readability,the coordinator 30 in FIGS. 11, 12, 13A and 13B is shown communicatingwith only one charger router 180 c, one EV router 176 c and one smartkey endpoint 172 c however the coordinator 30 communicates directly withall charger routers 180, all EV routers 176 and all smart key endpoints172.

Communication between each of the routers and endpoints in the meshnetwork 170 occurs in a daisy-chained fashion. For example the smart keyendpoint 172 a can communicate with the charger 180 a through the EVrouter 176 a or though the EV router 176 b. The mesh network 170 istolerant of high latencies and low data rates between routers andendpoints. The inherent redundancy of the mesh provides for faulttolerant operation and scalability. Additional chargers 14 can easily beadded or chargers 14 taken down for maintenance without adverselyaffecting the other chargers 14.

In one embodiment each EV router 176 is a single receptacle 18 on the EV12. Accordingly, the receptacle 18 on the front of an EV 12 can becoupled to a charger 14 but a second receptacle on rear or side of theEV 12 can retransmit data from the charger router 180 or the smart keyendpoint 172.

The smart key 174 and the smart key endpoint 172 contain data associatedwith an account holder, typically the driver. The EV 12 or a receptacle18 thereon contains data associated with the EV 12. The separation ofdata associated with the account holder and the EV 12 provides for ashared car experience where a parent and a teenage driver can each usethe same car with separate keys for billing purposes or to storepreferences such as charging behavior. An account holder can also usethe smart key 172 in a rental car scenario or a borrowed car scenariofor billing and personalization.

When the EV is parked and ready to be charged, the smart key 174 pairswith and activates a receptacle 18 to enable charging. The smart key 174can then be removed during charging. In one embodiment, the smart key174 is also the ignition key and automatically enables charging bydetecting when the ignition key has been removed from the EV 12. Uponreturning to the car, the driver inserts the ignition key and the smartkey 174 is updated with charging information from the charger 14 used tocharge the EV 12.

Each of the charger routers 180 monitors the signal strength of othercharger routers 180 and EV routers 176, and each of the EV routers 176monitors the signal strength of other charger routers 180, EV routers176 and smart key endpoints 172, and transmits the signal strengthinformation to the coordinator 30 directly or through a daisy chainedpath in the mesh. The coordinator 30 uses the signal strengthinformation to create a routing map of possible communication pathsbetween any of the elements in the mesh. The coordinator 30 alsocommunicates through the Internet 34 with resources including computers36 a and 36 b through the Internet gateway 32. In one embodiment, theInternet gateway is a computer configured as a file server. The routingmap can be a real time response or it can be stored in a database incommunication with the coordinator 30. For example, the routing map canbe stored on a computer 36 a or 36 b. Each of the charger routers 180,EV routers 176 and smart key endpoints 172 becomes aware of the possiblecommunication paths by receiving a beacon from the coordinator 30. Thebeacon is a packet of data containing the communication paths for eachelement in the mesh network 170.

FIG. 12 shows the mesh network 170 of FIG. 11 further including ametering architecture and additional Internet resources. The chargingsystem 10 of FIG. 1 is designed to easily work with an existing powergrid 20 infrastructure. Each charger router 180 communicates with aphysical power meter 196 and with a physical legacy meter 198. Thelegacy meter 198 measures all power supplied to or from the power grid20. Each power meter 196 measures all power supplied to or from thecharger 14 including multiple charging sessions with multiple EVs 12.

In one embodiment, upon completion of a charging session with an EV 12 avirtual power meter 200 in communication with the coordinator 30 recordsthe power consumption of the power meter 196, which is transmitted bythe charger router 180 and associates the power consumption with theparticular EV 12 receiving or supplying power. The coordinator 30 thentransmits the power consumed to a virtual meter 194 associated with anEV 12 and to a virtual meter 192 associated with an account holder. Thevirtual meters 192, 194 and 200 appear as physical meters to the meshnetwork 190 but store data representing power supplied or power consumedin non-volatile storage. In one example, the non-volatile memory isFlash memory.

The physical meters 196 are read with automatic meter reading (AMR),which is a wireless protocol to transfer the power meter data to thecharger router 180. The coordinator 30 monitors and records theaggregate power consumption or transfer from information sent by thepower meters 196 to determine the amount of power consumed ortransferred to the power grid 20 exclusive of regular premise useoutside of the charging system 10, for example an industrial plant 201.

Data collected from each charging session is stored in a behaviorsmodule 204. In one embodiment the behaviors module 204 stores at leastone of the date, time and duration when the EV 12 was charged and thelocation where the EV 12 was charged. The collected data are useful forV2G to determine which EVs 12 can advantageously return power to thepower grid 20. The collected data can also facilitate targeted marketingto vehicle owners. In one embodiment, the coordinator 30 uses an arbiter206 to determine which EV 12 should supply power to the power grid 20and how it should do so. For example, one EV 12 may provide sufficientpower for V2G; however, several EVs 12 can be available to supply thenecessary power. In one example, the arbiter chooses an EV 12 that ismost likely to remain coupled to the charger 14 during an entirecharging session based on past charging behavior recorded in thebehaviors module 204.

The coordinator 30 also communicates with a validation module 202, whichstores account information required to authorize a charging session. Thevalidation module can also store parking infractions or other data thatcould prevent the EV 12 from using the charging services.

The validation module 202, behaviors module 204 and the arbiter 206 caneach include a single database containing data for all EVs 12 using thecharging system 10 or can include multiple databases, for example adatabase for each EV 12.

FIG. 13A illustrates an example of a communication path as described inFIG. 11. In one embodiment, each of the smart key endpoints 172, EVrouters 176 and charger routers 180 receives a beacon from thecoordinator 30 defining either preferred or available communicationpaths. The smart key endpoint 172 a and the EV router 176 a communicatethrough a wireless path 212. The EV router 176 a and the charger router180 a communicate through a wireless path 214. The charger router 180 aand the charger router 180 b communicate through a wireless path 216.The charger router 180 b and the charger router 180 c communicatethrough a wireless path 218 and the charger router 180 c and thecoordinator 30 communicate through a wireless path 220. In anotherembodiment, any of the smart key endpoint 172 a, the EV router 176 a orany of the charger routers 180 communicates directly with thecoordinator 30.

FIG. 13B shows the routing mesh network 210 of FIG. 13A to furtherillustrate how the communication paths are managed. In FIG. 13B thecharger router 180 b has failed, thereby breaking the daisy chained pathused in FIG. 13A. The coordinator receives signal strength informationfrom as least one of charger routers 180 a and 180 c one of EV routers176 a, 176 b or 176 c. In one embodiment, the coordinator 30 determinesthat the next best path from the smart key endpoint 172 a to thecoordinator 30 based on the loss of signal from charger router 180 b andsends a new beacon to all elements in the mesh network 210. Thedaisy-chained path is then modified to use EV router 176 b instead ofcharger router 180 b to complete the path. Accordingly, charger router180 a and EV router 176 b communicate through a wireless path 232, andEV router 176 b and charger router 180 c communicate through a wirelesspath 234.

Although wireless communication has been described throughout theembodiments and in further detail in FIG. 1, other communication pathsare contemplated. For example, one or more wireless path could insteaduse optical links or other spectral emissions of any frequency. Certainlinks could also be implemented with wired connections, for example path220 between the charger router 180 c and the coordinator 30.

In another aspect, as shown in the illustrations of FIGS. 14-20, thepresent inventive concepts feature a system and method for automaticcharger resource sharing to support one or more EVs simultaneously on atime-shared basis, also referred to as charger-resourcecongestion-management.

Applications of the automatic charger resource sharing system and methodcan relate to dynamic (short duration) parking scenarios, e.g., at acharging location at a parking lot or garage for a retail establishment,a highway rest stop fast-charge location, or static parking scenarios,e.g., overnight residential parking locations, and/or blended parkingscenarios, for example, a charging location at a workplace or airport.Features of the charger-resource congestion-management techniquesdescribed in accordance with some embodiments are important because theydramatically decrease the costs of EV infrastructure per user, i.e., Nchargers need to be installed to support M users; where N and M areintegers and where N<<M. This can eliminate the known problem of“charger hogs”, for example, at a charging station. In addition tocapital-cost reductions, its automated nature will provide foroperational cost reductions for fleet servers/operators (i.e. no humanlabor is required to execute the allocation of the limited resource).

FIG. 14A is an illustrative front view of two electric vehicles (EVs)312A, 312B (generally, 312) proximal to a charger 314 at a parkinglocation, in accordance with an embodiment. FIG. 14B is a top view ofthe two electric vehicles 312 proximal to the charger 314 at the parkinglocation shown in FIG. 14A. Although two EVs 312A, 312B are shown, fourEVs 312 or more can be proximal to a single charger 314, for example,EVs 312A-312D shown at FIGS. 16A and 16B, each having a chargingreceptacle for receiving power or the like from the charger 314.

As shown in FIGS. 14A and 14B, each EV 312 is configured with areceptacle 318A, 318B, respectively (generally, 318) constructed andarranged for receiving electricity or related power for charging thecorresponding EV 312. The charger 314 can be the same as or similar torobotic chargers in other embodiments of the present inventive concepts.The charger 314 can include a robotic arm 317 having an extent of reachidentified by locations proximal to the EV receptacles 318. Thearticulating arm 317 of the charger 314 can extend and retract to be ator proximal to the first EV 312A and/or the second EV 212B, for example,shown at FIGS. 15A and 15B. In addition to the articulating arm 317 caninclude one or more joints or the like providing the robotic arm 317 iscapable of articulated movement with six degrees of freedom (sixDOF),similar or the same as other embodiments herein. Robotic arms withadditional degrees of freedom are also envisioned. While preferably asixDOF robotic arm is used, certain installations may advantageously usea robotic arm with more joints to clear obstacles between the charger314 and the one or more EVs 312.

In some embodiments as shown in FIGS. 14A and 14B, a base of the charger314 can be coupled to a ground surface. In other embodiments as shown inFIGS. 15A and 15B, a base 315 of the charger 314 can be at or near asurface 302 such as a curb, wall, or other side surface.

FIG. 17 is a flowchart of a method 350 for dynamic allocation of acharging resource, in accordance with some embodiments. In describingthe method, reference is made to elements of the charger 314 of FIGS.14-16. For example, some or all of the method can be performed insoftware running on a computer processor of the charger 314 of FIGS.14-16, for example, the resource management device 330 shown in FIG.14A. However, the method 350 is not limited thereto, and thus, chargersor the like in accordance with other embodiments can equally apply.

In an embodiment, the method 350 dynamically allocates finite chargerresources, e.g., in pre-allocated time slots, and capacity, e.g., inWatts or related units of measurement, across one or more EVs presentfor charging, for example, recharging a battery of an EV 312. Roboticmechanisms in the charger 314 are utilized as actors to implement theresource sharing activities. In other embodiments, the allocation ofcharging resources can be reset with any change in circumstance, such asEVs pulling away from a served parking position.

At block 352 of the method 350, a robotic charger 314 is shared betweenEVs 312, for example, between 1-4 EVs 312 as shown in FIGS. 14-16. Here,a predetermined charger capacity is served to each EV 312. The chargercapacity for a given EV 312 can be set to a maximum electrical energyamount that the individual EV 312 will support. The charger 314 and/orthe EV 312 can include a sensor or the like, for example, RFemitter/detector, for sensing when the charger 314 as proximal to orinserted into the EV's receptacle 318, for example, similar or same asother embodiments herein.

At block 354, a time slot is provided for the allocation of electricalenergy to one or more of the EVs 312. Here, the resource managementdevice 330 divides a predetermined amount of time into units of time,also referred to as time slots or slices. Each unit of time is availableto each and every EV 312 in communication with the robotic charger 314for receiving an allocation of electrical energy at the time slot. Insome embodiments, each unit of time is the same, i.e., the length oftime is the same. Alternatively, the units of time can be different. Theunits of time can be allocated according to specific minimum timeslices, for example, 0 seconds.

At block 356, the EVs 312 bid for an allocation of electrical energy atthe time slot. For example, each EV 312A-D shown herein can bid for a 1minute allocation of electrical energy. The resource management device330 can also control a rate, amount, or the like with respect to theallocation of electrical energy during the time slot. Upon accepting thebid inquiry, the charger 314 can charge the bidding EV 312 according toan allocated unit of time. The allocated time-slices to a served EV 312can be increased at a fixed (implementation specific) increment, untilthe charging capacity of the served EV 312 is reached. Accordingly, atblock 360, the charger 314 charges at least a portion of a battery ofthe EV 312 the wins the bid. Details on the bidding process aredescribed in FIG. 18. As described in FIG. 18, an EV 312 that is fullycharged has no need for receiving the charger resource, and thereforeceases to bid for a time slot allocated by the charger resource.

FIG. 18 is a flowchart of a method 380 for determining a bidder forreceiving an allocation of a charging resource, in accordance with someembodiments. For example, some or all of the method can be performed insoftware running on a computer processor of the charger 314 of FIGS.14-16, for example, the resource management device 330 shown in FIG.14A. However, the method 350 is not limited thereto, and thus, chargersor the like in accordance with other embodiments can equally apply.

At block 382, a context setting that defines metrics, measures, or thelike, is provided which can be used for decision making with respect todetermining a bidder for receiving an allocation of a charger resourcesuch as electrical energy in a given time slot, for example, generatedaccording to the method 360. In some embodiments, a high miles per hourcharge (MPHC) EVs is favored as a function of a state of charge (SOC),but can also apply low MPHC EVs, and also low state of charge (SOC) EVs.As a state of charge (SOC) percentage increases at a given charge rate,the MPHC will decrease, as is well-known to those of ordinary skill inthe art with respect to car batteries or the like. In some embodiments,a particular EV time waiting while not charging, described below, ismonitored to provide balanced sharing between the EVs 312.

Elements of block 382 can include enumerated limits. In someembodiments, demand response electricity pricing or elastic demand mayapply if the dynamically set price of electricity, e.g., measured incents/kwh, is high for an individual EV 312, for example, as set byhuman operator of that EV(i)) then that EV(i) will be disfavored in thebidding. In other embodiments, a limit can be imposed according tocurrently available energy, or state of charge. Here, energy needed fornear-term driving needs is based on recent behavior.

At block 384, an EV 312 is selected for presenting a bid for anallocation of electrical energy in a time slot, where i=1 referring to afirst EV of a plurality of EVs. At block 386, a bid (bid(i)) iscalculated to charge a particular EV(i) during a time slot. In someembodiments, following equation (Eq: 1) in performing a bidding step:bid(i)=(c0*MPHC(i)+c1*TWS(i)+c2*(1−SOC(i))+c3(demandprice(i)−actualprice)+c4*rand( ))  Eq.: 1:

-   -   if SOC=1 (i.e. fully charged) bid(i)=0    -   max bid (i)I=1→ 4 is awarded the time slot; robotic charger        charges EV(i) for that time slot    -   go to step 358, where bid(i) is determined

Accordingly, Eq. 1 determines a calculated bid (bid(i)) to charge aparticular EV 312 during a unit of time, also referred to as a slice oftime. For method 350, in particular, Eq. 1, “SOC(i)” refers to a stateof charge (%), where t(i)=n(i)*T, where “t” refers to continuous time(for example, seconds), “t(i)” refers to time for an EV, “n(i)” refersto a number of total time units allocated to one EV, i=1 4, “T”→refersto a time slice length, and t=sum t(i). Also, “TWS (i)” refers to timewaiting in spot, while not charging (for example, seconds). Also,“demandprice (i)” refers to the price EV(i) is willing to pay forelectricity, “c0” refers to a bid coefficient for the effect of MPHC(i),high MPHC is favored for bidding, MPHC(i) will decay with increasing SOCso that inherently high MPHC EVs do not “hog” from inherently low MPHCEVs, “c1” refers to a bid coefficient for time waiting TWS(i) for aparticular EV(i). An EV that has waited too long gets favored, “c2”refers to a bid coefficient for the SOC(i) of a EV(i). A particularEV(i) that needs more charge (has a lower SOC(i) will be favored. Notethe detailed of the term (1−SOC(i)), “c” refers to a bid coefficient forallowing EV(i) to disfavor charging if electricity prices are higherthan desired. However, there is still a chance that charging will occurat when actual price exceeds demand price, and “c4” refers to a bidcoefficient to induce random perturbations to ensure “race conditions”can be broken. The bid coefficient “c4” can be set to 0 in someembodiments.

At decision diamond 388, a determination is made whether a state ofcharge of the EV is 1, or 100%, indicating for example, that the EVbattery is fully charged. If yes, then the method 380 proceeds to block390, where bid(i)=0, indicating that the EV is removed from the biddingprocess. Otherwise, the method 380 proceeds to block 392, wherein adifferent EV is selected for bidding for the allocated resource. Atdecision diamond 394, a determination is made whether the number of EVsbidding for the allocated resource in the time slot is at a maximum, forexample, 4 EVs have provided bids according to Eq. 1. If yes, then themethod 380 proceeds to block 396, where the highest bidder isdetermined, and the selected EV is charged for the time identified bythe time slot.

FIG. 19 is a diagram of a kinematic model of a charger, in accordancewith an embodiment. FIG. 20 is a diagram of the kinematic model of FIG.19 and corresponding elements of a charger, in accordance with anembodiment.

The charger can include a linear element 402 and three rotating joints404, 406, 408. The linear sliding element 402 can move linearly alongits own axis. The rotating joints 404, 406, 408 can each rotate aboutits own axis. The rotating joints 404, 406, 408 can include one or morestepper motors or the like. Collectively, the linear element 402 andthree rotating joints 404, 406, 408 can form an articulating arm of thecharger and can provide four active degrees of freedom, referred to asfour degrees of freedom selective compliant articulated robot arm(SCARA), which can be applied to an articulating arm such as the roboticarm of the charger illustrated at least at FIG. 20.

Other degrees of freedom, referred to as passive degrees of freedom, canbe provided that are not actuated by a motor that otherwise generates amotion in at least one of the linear element 402 and three rotatingjoints 404, 406, 408. A passive degree of freedom can relate to onespring loaded angle or pitch. Another passive degree of freedom canrelate to one unconstrained movement, such as a roll.

The charger can be coupled to a reference ground 420 for fixedpositioning of a base of the charger (not shown) from which the linearelement 402 and three rotating joints 404, 406, 408 can move relative tothe base and to each other, thereby providing the abovementioned sixdegrees of freedom. An electrical connector 410 can be included, whichcan be similar to other electrical connectors described herein. Detailsof the electrical connector 410 are therefore not repeated due tobrevity.

As shown in FIG. 19, the rotating joints 404, 406, 408 can correspond torobotic joints 414, 416, 418, respectively, of an articulating arm of acharger, and linear element 402 can correspond to a linear actuator orthe like 412 at an end of the articulating arm.

FIG. 21 is a table illustrating a comparison of utilization of chargerresources, in accordance with some embodiments. The EV charger sharingsystems and methods are constructed to maximize the utilization ofcharger resources, which is important to ensure that a maximum usersatisfaction can be delivered at the lowest capital investment cost.Accordingly, the table illustrates benefits of sharing yielding bettercapital resource utilization with regard to the present inventiveconcepts (column entitled “PowerHydrant”) over conventional poweroutlays to electric vehicles.

The table in FIG. 21 illustrates two use-case scenarios. The first is anormal charge rate long-term charging window, or workplace chargingscenario. Here, provided is a 10 kw charge rate capability in eachcharger, and a charge demanded by each EV of 21.25 kwh need. An 8 hourcharging time window is available.

The second use-case scenario includes a fast Charge Rate Short-termcharging window, or roadside charging scenario. Here, provided is a 200kw charge rate capability in each charger, and a charge demanded by eachEV is 21.25 kwh need. A 30 minute charging time window is available.

The “work-hours (w-h) deliverable” (whb) reference refers to the totalenergy that can be delivered (capacity) by a charger during the chargingtime window. The charging time window is a representative amount of timethat a user could be expected to stay at the charger. E.g., 8 hours at awork place, 12 hours at home over night, 30 minutes for a roadside stop.

The cell marked “w-h delivered” (whd) refers to the total energy thatactually has been delivered. The whd value may be lower than the whbvalue because there is less demand than capacity. If the whd value issignificantly lower than the whb value, then utilization or “utility” isadversely effected. This is almost always the case when one charger isallocated to one EV. This is the core rational for sharing in accordancewith embodiments of the present inventive concepts.

The cell marked “w-h demanded” (whm) refers to is the energy demanded bythe total number of EVs being served by a charger.

“Aggregate customer satisfaction” (acs) is provided where:acs=1−(whm−whd)/whm) is a measure of customer satisfaction that startsat 1, and is subtractively offset by a ratio of unmet-demand to demand.The goal of any system is to achieve high utilization while coming asclose as possible to acs=1.

The cell marked “utility” (whd/whb) is a simple ratio of deliveredenergy in aggregate to deliverable capacity. A low ratio indicates poorutilization of resources. A high ratio indicates good utilization ofresources but is measured against customer satisfaction. The utility canrelate to a customer getting what he or she needs while maximizing theutilization of a resource.

The cell marked “maximizing satisfaction against capital cost “utility””(acs*whd/whb) refers to the scaling of utilization by customersatisfaction. That is utilization scaled by satisfaction.

While the invention has been shown and described with reference tospecific preferred embodiments, it should be understood by those skilledin the art that various changes in form and detail may be made thereinwithout departing from the spirit and scope of the invention as definedby the following claims.

What is claimed is:
 1. An electric charger resource sharing system,comprising: a charger that supplies electrical energy to a plurality ofelectric vehicles, the charger including: a robotic arm that articulatesto be proximal to each of the electric vehicles for supplying theelectrical energy to the electric vehicles; and a docking interface at adistal end of the robotic arm that couples with a receptacle on each ofthe electric vehicles for transferring the electrical energy from thecharger to the electric vehicles; and a resource management device thatreceives a bid from each electric vehicle, compares the bids to eachother, and allocates a portion of the electrical energy for apredetermined period of time to an electric vehicle of the plurality ofelectric vehicles having a highest bid of the compared bids in responseto the bids of the electric vehicles.
 2. The electric charger resourcesharing system of claim 1, wherein the resource management devicedivides a period of time into a plurality of time slots, wherein thepredetermined period of time is a time slot of the plurality of timeslots, and wherein the robotic arm is allocated to the electric vehiclefor receiving the allocated portion of the electrical energy in the timeslot.
 3. The electric charger resource sharing system of claim 1,wherein the resource management device removes an electric vehicle froma bid selection in response to a determination by the resourcemanagement system that the electric vehicle has a maximum state ofcharge.
 4. The electric charger resource sharing system of claim 1,wherein the maximum state of charge is 100% or a manufacturer-specifiedfull charge.
 5. The electric charger resource sharing system of claim 1,wherein the charger further comprises a base coupled between the roboticarm and a stationary ground or wall surface.
 6. The electric chargerresource sharing system of claim 1, wherein the robotic arm includes aplurality of joints for articulating the robotic arm at least at fourdegrees of freedom to couple with each electric vehicle.
 7. The electriccharger resource sharing system of claim 5, wherein the joints includerotating joints that include one or more stepper motors for rotating thejoints about their own axes.
 8. The electric charger resource sharingsystem of claim 1, wherein the plurality of electric vehicles includesone to four electric vehicles.
 9. A method for selecting an electricvehicle for receiving an allocation of a charging resource, comprising:selecting each of a plurality of electric vehicles as a candidate forreceiving an allocation of a charging resource for a predeterminedperiod of time; generating by a computer processor a bid value for eachof the plurality of electric vehicles; and selecting in response to ahighest bid determined from the bid values one of the electric vehiclesfor receiving the allocation of the charging resource for thepredetermined period of time in response to the bid value correspondingto the one of the electric vehicles; and providing, by a charger havinga robotic arm, the allocation of the charging resource for thepredetermined period of time to the selected one of the electricvehicles.
 10. The method of claim 9, further comprising: assigning atime slot for the allocated portion of the electrical energy.
 11. Themethod of claim 9, further comprising providing a charger constructedand arranged to supply electrical energy to a plurality of electricvehicles.
 12. The method of claim 9, wherein the bid value is a functionof a current state of charge.
 13. The method of claim 12, wherein anelectric vehicle with a maximum state of charge is withdrawn as acandidate for receiving the allocation of the charging resource.
 14. Themethod of claim 9, further comprising dividing a period of time into aplurality of time slots, wherein the predetermined period of time is atime slot of the plurality of time slots, and wherein the robotic armdirectly couples to the selected electric vehicle for receiving theallocation of the charging resource.
 15. The method of claim 9, whereinthe plurality of electric vehicles includes one to four electricvehicles.
 16. A computer program product for selecting an electricvehicle for receiving an allocation of a charging resource, comprising:a non-transitory computer readable storage medium having computerreadable program code embodied therewith, the computer readable programcode comprising: computer readable program code configured to selecteach of a plurality of electric vehicles as a candidate for receiving anallocation of a charging resource for a predetermined period of time;computer readable program code configured to generate a bid value foreach of the plurality of electric vehicles; and computer readableprogram code configured to compare the bids to each other, and selectone of the electric vehicles having a highest bid of the compared bidsfor receiving the allocation of the charging resource for thepredetermined period of time in response to the bid value correspondingto the one of the electric vehicles.